The subject matter disclosed herein relates to single photon emission computed tomography (SPECT), and more particularly to adjustable SPECT detectors.
A wide range of imaging techniques are known and currently in use, particularly for medical diagnostic applications. One such technique, SPECT, relies on the emission of gamma rays during the radioactive decay of a radioisotope (or radionuclide), commonly administered in the form of a radiopharmaceutical agent that can be carried, and in some cases, bound to particular tissues of interest. A SPECT scanner detects the emissions via a gamma radiation detector that typically includes a collimator, a scintillator, and a series of photomultiplier tubes. The collimator allows only emissions in a particular direction to enter into the scintillator. The scintillator converts the gamma radiation into lower energy ultraviolet photons that are detected by the photomultiplier tubes. These, in turn, generate image data related to the quantity of radiation impacting the individual regions. Image reconstruction techniques, such as back projection, may then be used to reconstruct images of internal structures of the subject based upon this image data.
While such systems have proven extremely useful at providing high quality images with good diagnostic value, further refinement is needed. For example, existing SPECT scanners may include one or more detectors that are rotated about the subject. Such systems may be complicated and costly because of the need for electro-mechanical components to rotate the detectors. In addition, some subjects may not be comfortable with having detectors moving around them. Furthermore, existing SPECT detectors may be flat and relatively large to be able to image a wide range of subjects. However, because of the irregular shape of subjects, only a small portion of such SPECT detectors may be brought into close proximity with the subject. Peripheral areas of these SPECT detectors may provide lower quality images of the subject. Smaller SPECT detectors may address some of these issues, but such detectors may lack a large field of view. For example, small SPECT detectors may not be capable of imaging an entire subject at once. Thus, some subjects may be made uncomfortable by the increased imaging time made necessary by small SPECT detectors. Improved SPECT scanners are needed that will permit high quality imaging of large fields of view of a variety of subject sizes and avoid such drawbacks in the prior art.